
    <!DOCTYPE html>
    <html lang="zh-CN">
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>tomcat如何优化？ - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
        }
        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
        }
        .report-actions button.primary:hover {
            background-color: #218838;
        }
        
        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>tomcat如何优化？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在Tomcat的整体架构中，哪个组件是核心的Servlet容器，负责管理Servlet的整个生命周期？",
    "options": [
      "Jasper",
      "Coyote",
      "Catalina",
      "Cluster"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Catalina是Tomcat的核心组件，它作为一个Servlet容器，负责处理传入的请求，并根据web.xml的配置将请求映射到具体的Servlet进行处理。它管理着Servlet从加载、初始化到服务和销毁的整个生命周期。",
    "source": "文档中「Tomcat 的整体架构」部分的 Catalina 描述",
    "hint": "文档中将这个组件描述为 Tomcat 的“心脏”，并提到它提供了对 Servlet API 的完整实现。"
  },
  {
    "question": "在配置Tomcat集群时，如果一个Web应用需要确保同一用户的连续请求都由同一台服务器处理，以利用本地会话缓存并减少网络开销，应优先选择哪种负载均衡策略？",
    "options": [
      "轮询 (Round Robin)",
      "最小连接数 (Least Connections)",
      "IP 哈希 (IP Hash)",
      "加权轮询 (Weighted Round Robin)"
    ],
    "correctAnswerIndex": 2,
    "explanation": "IP 哈希 (IP Hash) 策略根据请求来源的IP地址计算哈希值，然后将请求固定分发到集群中的某一台服务器。这确保了来自同一用户的请求始终由同一台服务器处理，非常适用于需要保持会话状态（即会话粘性或Sticky Sessions）的应用场景。",
    "source": "文档中「2.1 常见负载均衡算法」部分",
    "hint": "思考哪种算法能将来自特定来源的请求“绑定”到固定的服务器上，文档中描述它'适用于需要保持会话状态的应用'。"
  },
  {
    "question": "文档中提到了两种Tomcat自带的会话复制管理器：DeltaManager 和 BackupManager。对于一个节点数量非常多的大规模集群，为了提升会话复制的性能并减少网络开销，应选择哪一个？",
    "options": [
      "DeltaManager，因为它能实时将变更复制到所有节点，保证最高的一致性。",
      "BackupManager，因为它采用异步方式，只将状态复制到指定的备份节点。",
      "两者皆可，因为它们的性能差异在高负载下不明显。",
      "Sticky Sessions，因为它完全避免了会话复制。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "BackupManager采用异步复制机制，它只将会话的变更状态复制到一个指定的备份节点，而不是像DeltaManager那样广播给集群中的所有节点。这种方式大大减少了网络流量和处理开销，因此更适用于节点众多的大规模集群环境。",
    "source": "文档中「3.1 会话复制」部分的 BackupManager 描述",
    "hint": "寻找那个被描述为'异步复制'且'适用于大规模集群'的会话管理器。"
  },
  {
    "question": "在对Tomcat进行JVM参数优化时，文档建议将初始堆大小（-Xms）和最大堆大小（-Xmx）设置为相同的值，这样做的主要目的是什么？",
    "options": [
      "为了让垃圾回收器（GC）更频繁地执行，从而释放更多内存。",
      "为了在启动时立即占用最大内存，防止其他应用抢占资源。",
      "为了防止JVM在运行时动态调整堆大小，避免由此带来的性能开销。",
      "为了简化配置，因为这两个参数在现代JVM中作用相同。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "当JVM的堆内存大小是可变的时，如果当前内存不足，JVM会进行堆扩展；如果内存有较多空闲，可能会进行堆收缩。这两种操作都会触发STW（Stop-The-World），暂停应用线程，带来不必要的性能抖动。将-Xms和-Xmx设置为相同的值，可以避免这种动态调整，从而提高系统稳定性。",
    "source": "文档中「1.1 堆内存（Heap Memory）配置」部分",
    "hint": "文档提到，这样做的目的是'避免频繁的堆扩展操作'。"
  },
  {
    "question": "根据文档中对日志框架的对比，Log4j2相对于Logback在高性能场景下的一个显著优势是什么？",
    "options": [
      "Log4j2的XML配置文件比Logback更简洁易懂。",
      "Log4j2是Tomcat默认的日志框架，集成度更高。",
      "Log4j2内置了对异步日志的支持，可以显著减少日志记录对应用线程的阻塞。",
      "Log4j2支持更多的日志级别，如TRACE和FATAL。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中的对比表格明确指出，Log4j2的“异步支持”是“内置异步日志支持”，而Logback则需要外部依赖。异步日志允许应用程序将日志事件放入一个无锁队列后立即返回，由后台线程负责实际的I/O操作，这在高并发和对低延迟要求高的场景下是一个巨大的性能优势。",
    "source": "文档中「Log4j2 与 Logback 的对比」表格",
    "hint": "查阅文档中的对比表格，关注'异步支持'这一特性。"
  },
  {
    "question": "在优化Tomcat的Connector配置时，`maxThreads`参数扮演了什么关键角色？",
    "options": [
      "设置服务器能够接受的最大连接总数。",
      "定义了Tomcat启动时初始化的线程数量。",
      "控制了线程池中用于处理并发请求的最大线程数量。",
      "指定了单个请求处理的最长超时时间。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`maxThreads`参数用于设置Tomcat请求处理线程池的最大线程数。这个值决定了Tomcat能同时处理多少个请求。合理设置此参数至关重要，过小会导致请求排队，过大则会因线程切换开销和资源竞争导致性能下降。",
    "source": "文档中「2.1 HTTP 连接器配置」部分",
    "hint": "这个参数直接关系到Tomcat的并发处理能力，是线程池配置的核心之一。"
  },
  {
    "question": "当一个Web应用部署在Tomcat集群中时，使用Sticky Sessions（会话粘性）策略有什么潜在的缺点？",
    "options": [
      "它会因为频繁的会话数据复制而增加网络带宽的消耗。",
      "它需要配置复杂的外部共享存储（如Redis）来同步会话。",
      "如果某个Tomcat实例宕机，所有粘滞在该实例上的用户会话都会丢失。",
      "它会显著增加所有Tomcat实例的CPU和内存负担。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Sticky Sessions的优点是避免了会话复制的开销，但其主要缺点是破坏了负载均衡的完美性，并带来了单点故障风险。一旦用户的请求被“粘”在某台服务器上，如果该服务器发生故障，那么该用户的所有会话信息将丢失，需要重新登录，影响用户体验。文档中明确指出其缺点是“增加了单点故障风险，负载不均衡”。",
    "source": "文档中「3.3 Sticky Sessions」部分",
    "hint": "考虑一下当用户的请求被固定到一台服务器后，如果这台服务器出现问题会发生什么。文档中提到了'单点故障风险'。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  